As is known, a syndrome is a multidigit bit sequence corresponding to a correction factor for a particular error pattern. Upon determination of a Syndrome, a correction can then be made by assuming that a particular syndrome always comes about as a result of the presence of one particular error pattern.
The invention relates to a switching arrangement for correcting the polarity of a data signal transmitted with recurrent code; the data signal is made up of a sequence of bits which are introduced at the receiving end into a shift register having two or more trigger circuits. In the process, a syndrome is obtained from a syndrome generating switching stage.
As is generally known, in the transmission of teleprinter-generated data via radio links the polarities of the data signal to be supplied at the sending end by the data source and of the data signal applied at the receiving end to a data sink must agree. When required, either one of the polarities may be changed by means of polarity-adjusting devices at the send-side modulator and at the receive-side demodulator, and in this way the correspondence between the two polarities can be established. This manual correction of polarities known from the prior art causes a certain loss of time and requires skilled personnel if frequent changeovers from a receiving station to various transmitting stations must be performed in complex data transmission systems.
It is an object of this invention to provide for a switching arrangement which monitors polarity during the transmission of a data signal with a recurrent code and automatically corrects it, if necessary.